Hydraulic control system



Ost. l, 1940.

J. B. PARsQNs HYDRAULIC CONTROL SYSTEM 2 Sheets-Sheet 2 Filed June 1, 1938 INVENTOR. BY Jw -.f:a/-som, f MJ @ma L ATTQRNEYJ.

Patented Oct. l, 1940 UNITEDSTATES `'inznmiumo CONTROL sfirsl'rnivr y n John B. Parsons, Indianapolis, Ind.: j l Application JnefL'isss, s'eria1No.`211,1lfc9 14 claims. (Gmac-15 Itis not onlyinconvenient, but actually dan` gerous, for ,the driver of anautomobile to be forced to operate., any of the windows of the automobile except that which is most closely adjacent an a utomot ive vehicle,.for controlling the ywin-4 dows of the vehicle. It isa further object of the invention to provide a hydraulic system of the character abovegsuggested in vwhich the auto' mobile starter motor is used to supply thenecessary, power. A s till further object of the invention is `to provide hydraulic means for locking the windows of an automobile in` any desired position. u' y It vfill be `ibvious that the -,present invention is applicable primarily to the control of windows in automotive vehicles; but that itmay also be used to shift any desired element, whether in an automotive vehicle or in some other environment.v

Further objects of `the invention will appear as the description proceeds. c

To the accomplishment ofthe above and related objects, my invention may be embodied in the form illustrated in the 'accompanying drawings, attention being called to the fact,-`however, that the drawings are illustrative only,4 and-that change may be made in the specific construction illustrated and described, so long as the scope of the appended claims is not violated.

Fig. l is a diagrammatic view of one embodiment of the present invention,` onlyA one of fthe plurality of windowsV to be operated being illustrated; v

Fig. 2 is an enlarged sectional View of the flowcontrolling valve which forms an element'ofv the organization illustrated in Fig. 1;

Fig. 3 is a fragmental section similar to Fig. 2, the valve being shownin another position of adjustment;` 7

` Fig. 4 is an enlarged elevation of a switch assembly which may be used'in the organization of the present application;

Fig. 5 is a sectional view taken substantiallyhon tion "of a piece` of flexible tubing 24 which is Y,

the line .Iic54 of Fig. 4 and looking in the direction of the arrows; Fig.V 6is an y,enliirged longitudinal Vsection through afluid motor used'indtheinstallation,of the present invention; y 5 Fig. 'is anl en d elevation'of ythe same but look ing from the right of Fig. 6; yand f Fig. 8 is a' fragmental perspective view of an instrument board of an automobile, showing the control panel of the installation "illustratedin 10 Fial. f `In Figa. 1, I havershown a window III in thel left front door II of af standard automobile, said window I0 being provided with operating means, indicated generallybythe reference numeral I2, 15 and including a lever I3 which is connected, by a c link I4, for'op'erati'on by a4 iluid motor, indicated generally by the reference numeral I5, and illustrated'inl detail in Fig. 6.

Said motor comprises *a cylinder ISinwhichis 20 reciprocably mounted a piston IIprovided `with a stem or rod I8 projecting through one endy of thecylinder and directly connectedto the` link I4. The opposite end Aof the cylinder may preferably `be ciosedby pinching thewaiis of the tube, 25 as indicated at I9 inFigs. 6 and '7,k and `welding Y the parts in the illustrated. positions. Preferably, a notch is cut'in the closed end of the cylinder so formed, to accommodateashortpiece of tubing 20 formedwith a bore-2 I said tubing being weld-l 30 ed in place during the 4closing operation. This y arrangement providesa journal mounting for the motor, abolt or screw being passed .through the bore 2 I` of the element 20 and beingV suitably` secured in place on the automobile door. In transverselyv aligned apertures formed in the tube I6 upon an axis perpendicular tothe axis'of the elementl, there is mounteda tube 22 which, at its lower end,ris.reducedas at 23 for therecep- 0 held in place bya clamp ring 25 of desired sharif acteristics. Within the cylinder I6, said Vtube'isy formed with one ormore ports 26;` and the slioulder formed by the reduction 23 'is preferablyy formed as a valve seat 21, with which cooperatesv 5 la reciprocating valve' 28.: A stem v29*oi"`this valve constitutes the core vof fa solenoid 3|);k and the valve is urged toward the closed position by a springA 3|` received betweenv the stem 29 and'V 50 plug 32 threaded into the bore of the solenoid. Obviously, upon'energization of the solenoid 30, the valve28 vwill be lifted off itsseat 2I Ito [estab-'- lish communicationbe'tween the tube 24l andthe interim of the murder is'. ,j l 5r A reservoir is conventionally illustrated at 33 in Fig. l. The principles of the present invention may obviously be applied to a. pneumatic system; but I have illustrated a hydraulic system which,

in my present opinion, is preferable. Obviously,

in a pneumatic system, no reservoir .will be necessary; and even in a hydraulic system it is not essential that a separate reservoir be provided; since brake fluid may be drawn from the conventional brake-system reservoir for usein the Pres-.- ent system, or oil may be drawn from the crank case for a like use. f

A pump 34 of desired characteristics forms an essentiaLelement of the present invention. Obviously, any type of fluid pump may be used, and any means may be provided for driving it; but I prefer to use a rotary pump; and I believe that, in the interest of economy, it will be highly de-V sirable to use the motor-uniformly provided for starting the' internal combustion engine of the automotive vehicle, to supply the powery for driving the pump. In Fig. l, therefore, I have illustrated the pump 34 quite conventionally; and I have shown it directly associated with the stand# ard starter motor 35. A valve, indicated gen-v erally at 36, is directly associated with the pump andcomprises means for .controlling the fluid flow during pumpv operation. This valve is iliustrated in datan in Figs. 2 and a. o

A casing 36 is formed with a port 31 with which is connected a pipe 38 providing communication with the reservoir 33. One end of the casing 36 is'closed by a plug 39, and the opposite end thereof is closed by a plug 40 which is formed with a longitudinal bore 4| whichvco'rnprises an axial port for the casingl 36, and in which :is received a conduit 42.

The casing 36 is further formed with a port 43 which communicates with the intake of the pump 34; and with a port 44 which communicates with the outlet'of said pump. It will be seen that the ports 43 and 44 are axially spaced radial ports and that the port 31 is a radlalportwhich is angularly spaced from the ports 43 and 44 but is positioned axially between said ports 43 and 44.

The casing is formed to `provide a chamber which, in the illustrated embodiment ofthe invention, consists of two parts 45 and 46, the former being somewhat larger in diameter than the latter, for a reason later to be explained. Reciprocably mounted within the chamber is a valve member 41 which isformed to provdeja piston head V48 within the chamber portion 45 and a piston head 49 within the chamber portion 46. The valve member 41 is further formed with a longitudinally extending bore 50 which is open as at 5| at the end adjacent the plug 40 and which is formed with` one or more ports 52 between the piston head 48A and the plug 40 and withk one or more ports 53 between the;piston head 49 and the' plug39. A spring 54 urges the valve 41 toward the position illustrated in Fig. 2, and the core 55 of a solenoid 56 is secured to the valve member 41 so that said valve member partakesmof movement of the core 55.

The conduit 42 is suitably branched into .any

motors associated` with three other windows ofw thevehicle (not shown) l Associated with the startervmotor 35 I have illustrated a mechanical-electrical switch 6I dominating the motor 35. 'I'he switch may be closed manually by depression of the plunger 62, or it may be closed electrically by energization of the solenoid indicated by the reference numeral 63. In the illustrated structure, an electrically insulated arm 64 is positioned between the plunger 62 and the lever 65 which is adapted to be actuated by the starter pedal 66. Depression of the pedal 66 ilrst throws a pinion on the motor shaft mechanically `intomesh with a gear on the ilywheel ofthe automobile engine (not shown) and then causes the lever to engage the arm 64 to move the same to depress the plunger 62 to energize the motor 35. Obviously, if the motor 35 is to be used to supply power to move the windows `of. the vehicle, it must be energized through somemeans other than the starter pedal 66,v so that the driving connection between the starter` motor and the vehicle engine will not be established at times when it is desired .to shift the windows. I

` In accordance with standard automotive practice, I use a single Wire system to control the organization of the present invention, all cir` cuits leading from the battery to ground. lThe switches which are mounted for convenient manipulation by the operator of the vehicleA are mounted upon a panel 61 which is grounded, as is illustrated; and the panel carries four switches, in the illustrated embodiment, the switch 68 being adapted to control the right rear window, the switch 69 controlling the right front windowfthe switch 10 controlling the left rear window, and the switch 1| controlling the illustrated left front window. Since the four switches are identical,

the switch 1I is illustrated in detail in Figs. 4 and 5; A' rockershaft 12, journalled in a block 15 `of insulating material mounted upon the rear of the panel 61, supports a metallic arm 13 Vwhich terminates in a finger piece 14 of insulating material. Two contact fingers 16 and 11 are mountand are identically mounted in the panel 61, only ed for engagement bythe inner end of the arm 13 upon downward movement of the finger piece 14, and one contact nger 18 is mounted for engagement by the inner end of the arm 13 upon upward movement of the -flnger piece14. The parts are so proportioned that, when the inner end of the arm 13 engages either the contact ele` ments 16 and 11 or the contact element 18, the outer end of the arm will simultaneously engage the metallic panel 61, whereby the engaged contact Vfinger is electrically connected to ground. The switch arm 13; is normally held in its illustrated neutral position by opposed coiledsprings |02 and |03.

The storage battery normally carried by an automotive vehicle is indicated by the reference numeral 19, and one side of the battery is shown as connected to` ground by a-wire 80. From the other'side of the battery a wire 8| leads to one terminal 82 of the solenoid 63 associated with the switch 6|. l l y terminalof said solenoid to the rock shafts 12 of the fourk switches 68, 69,710, and 1|. Obviously, then, movement of the switch arm 13 into engagement with thepanel 61 will close `a circuit through the solenoid 63 to closethe switch dominatingv the energizing circuit for the motorrr35, thereby starting said motor to drive the pump 34.

A wire 83 leads from the opposite A wire` 64 leadsfrom the contact nger 18 to one terminal 85 of the solenoid 3 0; vand the oppo-v site terminal 86 of said solenoid is connected to the `hot wire 8| by a wire 81. It will vbe clear, therefore, that upward movement of the finger closes the switch 6|, but also a circuit through wires 8| and 81, solenoid 30, wire 84, contact finger 18, arm 13, and panel 61 to ground, to energizethe solenoid 30 to lift the valve 28 controlling ow to the motor I5. The parts of the valve 36 being in the positions illustrated in Fig. 2,- operavtion of the pump will draw liquid from the reservoir 33 through port 31 and port 43 to the pump, and thence through port 44, ports 53, passage 50, and portto conduit 42. The valve 28 having ybeen lifted byenergization of -the solenoid 30, theliquid will flow through the branch 6l)v and flexible tube 24 into thecylinder I6 to move the piston |1 toward the left to raise the window I IJ.

As long as the arm 13is held in the abovementioned position, the pump will continue to operate to force liquid through the Yabovedescribed path, and the window I0 willcontinue to move upwardly either until the arm 13 is released or until the window strikes an obstruction which-may be the upper end of its frame. If the window does strike an obstruction, itwill be obvious that pressureywill build up in the chamberportion 46 above thepiston head 49 and in the chamberportion 45 belowthe pistonhead 48. Since the effective diameter of the piston head -48 isgreater than the effective diameter of the lpiston head 49, such a rise in pressure will overcome the tendency of .the spring 54 and will move .the valve 41 upwardly until the port 44 is partially uncovered by the head 49. In this position of the valve, liquid thrown b y thepump may pass directly from the port 44 to the port 43,*thus establishing a by-pass circuit, so that no damage will be done to the window or to the operating mechanism.

A wire 88 connects the contact ngers 16 of all of the switches 68, 69, 10, and 1| with one terminal 89 of the solenoid coil 56, the opposite terminal 90 thereof being connected to the wirev Therefore, if the finger piece 14 is depressed,

the -following circuits will ,be established. An

energizing circuit for thesolenoid 63 may be` traced from the battery 19 through Wire 8|, solenoid 63, wire 83, rock shaft 12, arm 13and panel 61 to ground.

At the same time, an energizing circuit the solenoid 56 is established from the battery 19 through wire 8|, wire 9|, solenoid 56, Wire 88. contact finger 16, arm 13, and panel 61 to ground.

At the same time, an energizingcircuit for the solenoid 30 is established from the battery 19 through wire 8|, wire 81, solenoid 36, wire 84, wire 92, contact finger 11, arm 13', and panel 61 to ground. Thus. the motor 35 is caused todrive the pump 34. Energization of the solenoid 56 having shifted the valve 41 to theposition of Fig. 3, operation of the pump 34 will tend todraw liquid from the pipe 42. The valve 28 having been opened by energization of the solenoid 30,

e liquid will be drawn from the cylinder I6, through branch 60 and pipe 42 and port 43 to the intake Y.

of the pump 34, and will be discharged through ports` 44 and 31 and pipe 38 to the reservoir 33.k Movement of the piston I1, toward the right will follow, and will cause counter-clockwise rnove.y

.portion 45 below the piston head 48 and `in the chamber section 46 above the piston head 49 *for . 65 to ground;` whereby the valve which, because of the ydifference in the effective areas ofthe piston heads will cause the valve 41 to move downwardly into the median posi` tion above described in which a short. circuit for the liquid propelled by. the pump` is established.

mth@ wiring diagram ofr'igfl' there are 1r- -lustrated two switches93 and 94. A wire 95-con-r nects therock shafts of the switches 93' and 94 withthe wire 83 and wire 91 connectsthe contact fingers 16 of the switches 93fand 94with the wire 88. A wire 96 connects the contact finger 11 of' the switch 93-with contact finger 18 .of switch `1|) andthe wire 98. connects the contact finger 18 of .the switch 93 withthe contact finger 18 ofswitch 10. Similarly, a wire 99.connects the Contact finger 11 of switch-94 to the kcontact finger.18 of switch 68, and the wirerl|00 connects the contact 1inger 18of,switch 94 with the-contact finger- 18 ofswitch 68. The switch I93 is positioned on the leftnreardoor, or adjacent thereto,l and the switch 94 is positioned onor adjacent theA right rear door, so that the occupants of the rear compartment'of the vehicle may operate their own windows, if desired., without disturbing thedriver ofthe'vehicle.

motor is usedv to..performv its normal function. f

The above-described safety feature of the valve,

36 will, of course, prevent .damage tothe system as aresult of such operationbut I am of the opinionA thatv the power demanded by the-.pump when the. valve 41 is in the position of Fig. 3 is somewhat less than'the power demanded. when the valve 41'i`sy in the` position of Fig. 2. 4Preferably, therefore; means will be provided for automatically'shiftingthe Vvalve 41 to the position of Fig. 3 whenever .the starter pedal 66 is operated.

In the illustrated embodiment of the inVen-' tion, a wire IUI provides van electrical connection between the terminal 89 of the solenoid 56 and the electrically insulated ,arm 64. The lever 65, on theother hand, is grounded upon the motor; -frame.k Therefore, when thestarter pedal 66 is depressed and the lever 65 engages the arm 64, an energizing circuit for the solenoid 56 is established from. thek battery 19 V through wire. 8|, wire 9|, solenoid 5,6, wire lIIJI, arm 6,4, and lever e 41 is moved to the position of Fig. 3. e y. l

The fact that the yvalvev casing 36 is constantly filled with oil causes'a dashpo't action which debecause it allows an instant delay after initiation of punp operation to facilitate movement of thev valves 28; and further because the dash-pot effect prevents accidental reverse movement. ofl the lwindow `at the lend. of downwardr movement thereof, which would occur if the valve 41 were., f

allowed to move to the position of Fig. 2 before operation of the pump hadcompletely stopped.

In Fig. 8 I have illustrated a suggested'ar-v rangement of thepanel, 61. and its associated control elements. The said panel-is set into the instrument board |04 with thefinger pieces 14, 14|, 142, and 143 projecting for convenient manipulation by the vehicle operator.- It Will be clear that the finger piece 14 will operate the switch 1|, the finger 14| will operate the switch energizing circuits.

erate-all four windows simultaneously by shifting` all four finger pieces with a single finger.

An important feature of the present invention lies in the provision of the valve 2t! associated with each of the fiuid motors.` Since these valves are spring pressed to closed position, it 4will be clear that as long as the manual switches are not disturbed, the windows will be'locked. -That is, since-liquid is trapped in the fluid motor cylindersrthepistons I1 'cannot bermoved against the liquid; and, since the said pistons are operatively connected to the windows,` the windows will be locked in any desired position'fofadjustment against movement toward open position,

Obviously, the device of the present application may be applied to any` desired number-of the windows of a vehicle, or itv may'beapplled to shift any other shiftable unit of ther vehicle. As obviously, although I prefer to -utilize the power'available in the starting motor to shift the windows, I may'use any other suitable source of power, such as an additional` motor, or power may be drawn from some rotating-part of the vehicle engine. Thus, either the starter motor or some part of the vehicle engine or an additional motor may be usedfto supply power toa fluid pump to drive fluid motors to shift desired elements, or any one of those power sources may be used to drive the shiftable elements directly through mechanical driving connections. Alternatively, but less desirably, individual electric motors,` independently controllable from a switchboard such as that illustrated herein,

might be provided for driving eachof the shift-v able elements.v

In certain of the claims appended hereto, reference is made to a vehicle having a plurality ofk windows, and means associated with each of said windows for shifting the same. It will be obvious that thi'slanguage means that a shifting means is -associated Ywith each of the plurality of windows referred to; and not necessarily with every window of the vehicle.

I claim asy my invention:

1. The combination with a movable closure of an electric motor, a pump connected to be driven thereby, a relay-controlled switch dominating said motor, a fluidV motor connected to operate said closure, a conduit leading from said pump to said fluid motor, a normally closed valve in said conduit adapted when closed to trap fluid in said fiuid motor thereby to retain the closure in the position of adjustment, electrically actuated means operable, upon energization, to open said valve, energizing circuits for said relay-controlled switch andfor said electrically actuated means, and switch means operable to close said 2. The combination with a movable closure of an electric motor, a pump connected to be driven thereby, a relay-controlled switch dominating said motor, a fluid motor connected to operate said closure, a conduit leading from said pump to said fluid motor,v valve means shiftable to reverse the direction of pumped nuid iiow in said conduit, anormally closed valve in said conduit adapted when closed to trap fluid in said fluid motor thereby to retain the closure in the position of adjustment, electrically actuated means operable, upon energization, toopen said valve,

said closure, a conduit leading from saidpump-to" said fluid motor, valve means-shiftbleto reverse the direction -of vpumped fluidy flow in said conduit, said valve means being biased towardone position of adjustment, electric means operable; uponv energization, to shift said valve Ameans against its bias to an opposite: position of adjustment, a normally closed valve' in Vsaid con-l duit, electrically actuated means operable, upon energization, to 'open said valve, energizing circuits' for said switch-operating' relay, for said electrically actuated means, and for said electric means, and switch means selectively operable to close all of said energizing circuits, or to close only the energizing circuits for said relay and for said electrically-actuated means.

4. In combination, a motor`,'a fluid Vpump operativelyconnected to be driven by said motor, a plurality of fiuid motors, means providing'fluid communication between said pump and said fluid motors, a valve disposed between said pump and said motors and shiftableto determine the direction of fluid flow between said pump and said motors, electric rmeans for shifting. saidv valve, and switch means movable in one direction' from a neutral positionto effect operation of said first-named motor and to energize said electric means, and movable in another direction from a neutral position to effect operation of said first-named motor without energizing said electric means.

5. The combination with a movable element of a fluid motor operatively connected to move said element, a fluid pump having fluid communication with said` motor, means for driving said pump, and means for controlling the 'direction of fluid flow between said pump and motor, comprising a cylinder provided with a rst radial port communicating with the intake of said pump, a second radial port communicating with the outlet of said pump, a third radial port angularly spaced from said first and second ports and located axially between the same,v and an axial port, a valve reciprocable in said cylinder andA provided with a'piston head shiftable from' a position between said firs-t port and said" axialy port toa position'between said first port and said third port, and with another piston headr of les's effective area shiftable from a'position between said second port and said third port to a position spaced from said third port by said second port, said valve further being formed with an 'axial bore opening into said cylinder at points between said heads and the adjacent ends of said cylinder.

`6. In an automotive vehicle havingan engine and a movable closure, an unidirectional electric motor for driving said'engine, mechanism providing an operative connection between said motor` and the movable closure, said mechanism comprising a hydraulic pump operatively connected to said motor, afluid motor operatively connected to said closure, means providing communication between said pump and fiuid motor,

the-direction of liquid, now to saicrnuid motor,`

electric means controlling said' valve', a normally closed valve'associated withl saidfluid motor,v

electricmeans for actuating said normally closed valve, energizing circuits for said motor, for said pump valve and for said fluid motor valve, and switch means for selectively closing all of said circuits, or to close only the circuits for said motor and said uid motor valve. i

7. 'I'he combination with a movable closure of an electric motor, a pump connected to be driven thereby, a relay controlled switch dominating saidmotor, a fluid motor connected to operate said closure, a conduit leading from said pumpto said fluid motor, valve means shiftable to reverse the direction of pumped fluid flow in said conduit, electrical means for actuating said valve,

a second valve in said conduit in advance of said first valve, means closing said lsecond valve when said pump is inactive, positive means for opening said second valve upon operation of said pump,

energizing circuits for said relay-controlled `switch and said electrical means, and switch means operable to close both of said energizing circuits.

,8. In an automotive vehicle having a movable closure, an engine, a starter motor for the engine, mechanism vfor actuating said closure from said motor, said mechanism comprising a hydraulic pump operatively connected to said motor,

\neans responsive to liquid under pressure for -energizing circuits'for said motor, for said electric means, and for said electro-responsive means', and switch means selectively operable to close all of said energizing circuits, or to close only .the energizing circuits for said motor and for ,said electro-responsive means.

9.`In an automotive vehicle having a' movable closure, an engine, a starter motor for the engine, mechanism for actuating saidv closure from said motor, said mechanism comprising a hydraulic` pump operatively connected to said motor,mean`svv responsive to liquid under pressure for operating said closure, meansproviding a conduit between said pump and closure operating means, a iiow control valve for reversing the liquid flow through said conduit, spring means normally holding said valve in one position, electric means including a solenoid for actuating said valve to theopposite position, a normally closed valve associated'with said operating means, electro-responsive means` `for opening said valve, energizing circuits for said motor, for said electric means, and for said electro-responsive means, and switch means kselectively operable to close all of said energizing circuits, or to closeronly the energizing circuits for said motor and for said electro-responsive means.

10. In an automotivev vehicle having a plurality of independently movable windows, a fluid motor operatively associated with each of said windows to move the same, an electrically controlled valve for each fluid motor, a pump having operative communication with all of said motors,

ai; ei'ectrlcauy' contfouedvawefassciated with l' said pump for controlling the ,fluid flow to and from: said fluidV motors respectively, a motor vfor driving` said' pump, energizing' circuitsfor said motor and each of said valves', andindependent switch means for eachfluid motor valvefor selec-y tively energizing oneof said iiuidfmotor valvesu and concomitantlyenergiz'i'g'said motor and lsaid pump valve for moving the window inrone direc'- 1 tion.

11. In an automotive vehicle having a plurality of independently movable windows, a uid motor operatively associated with each of said windows `to move the same, an electrically controlled valve for each iuid motor, a pump having operative communication with all of said motors, a flow control valve associated withsaid pump for controlling the fluid ow to and from said fluidy motors respectively, means for .yieldingly holding said valve in one position of adjustmentto cause fluid flow in one direction, electro-responsive means for actuating said valve to the other position of adjustment to cause fluid iiow in the opposite direction, energizing circuits for said motor and each of said valves, and separate switch means for each fluid motor valve for selectively energizing one of said fluid motor valves and concomitantly energizing said motor and electroresponsive means, thereby to move the respective window in one direction, or for energizing one of the fluid motor valves and concomitantly energizing said motor only, thereby vto move the respective window in the opposite direction.

l2. In an automotive vehicle having a plurality of independently movable closures, a unidirectional electric motor, ,a pump connected to be driven thereby, a relay-controlled switch dominating vsaid motor, a fluid motor operatively associated with each of said closures to move the same, conduits leading from lsaid pump to said `uid motors, valve means shiftable to reverse the direction of pumped fluid now in` said conduits,

said valve means being biased toward o ne posil tion of adjustment, electric means'operable upon energization to shift said valve means against its bias to an opposite position of adjustment, a normally closed valve for each of ysaid fluid motors, electrically actuated means for each fluid motor valve operable upon energization to open said valve, energizing `circuits for said switch operating relay, for each of said electrically actuated means, and for said electric means, and independent switch means for each electrically actu-- pump to said fluid motor, a normally closed valve, l

, in said conduit adapted when closed'to trap fluid in said fluid motor thereby toretain the member ina position of adjustment between the two limits, electro-responsive means operable, upon energiza- `tion, to open said valve, energizing circuits for said motor and electro-responsive means, and

Y switch means operable to close said energizing a uidmotor operatively associated with each of said windows, conduit means connecting` said pump and each fluid motor; a normally closed valve for each uidmotor arranged in said con-` duit means and adapted whenV closed Vto VtrapV uid inthe respective fluid motor thereby' to re tain the closure inthe position of adjustment,

electro-responsiveV means for` each valve adapted,` 

